Barwin can get away with playfully mocking Kubiak as long as he keeps producing on the field. The 6-foot-4, 268-pound outside linebacker had a breakout season in 2011, leading the league’s second-best defense with 111/2 sacks.

And with only two full seasons under his belt, the Texans hope his best years lie ahead.

“He went in, did such a great job last year, against really good people,” defensive coordinator Wade Phillips said. “He was always playing against the left tackle in passing situations, most of the time. The sky’s the limit for him. He’s about 270 pounds and he’s a really good athlete.”

The Texans began two-a-day practices on Saturday, with hundreds of fans packing bleachers on one side of the field. Barwin comes into this year’s camp with renewed confidence after last season, a bounce-back year after he dislocated his right ankle in the 2010 season opener.

“This camp’s a big difference than last year, obviously,” Barwin said. “You were unsure about my ankle, how I would respond to playing full-speed football. I come in a lot more comfortable than I did last year.”

When Phillips became the defensive coordinator and installed a 3-4 alignment, Barwin and Mario Williams moved from defensive end to outside linebacker. Williams tore a chest muscle in Week 5, and Barwin took advantage of the opportunity. He recorded sacks in three consecutive games to start November and set a single-game franchise record with four against Jacksonville.

Barwin says his personal goal this season is to prove last year was no fluke.

“Yeah, I’ve been given some compliments,” he said, “but there are a lot of guys in this league that came in and had 10-plus sacks in a season. There’s a big difference when you get back-to-back 10- plus sacks compared to guys that have done it once in their career. So I obviously want to build on that and not be a guy that’s just done it one year.”

Phillips doesn’t want Barwin to change a thing. Houston lost Williams in free agency, then drafted pass-rushing specialist Whitney Mercilus in the first round to join the rotation at outside linebacker with Barwin and Brooks Reed.

“He’s going to run people down from behind, he’s got to just keep doing what he’s doing,” Phillips said of Barwin. “He worked hard this offseason. He’s fast, he’s athletic.”

Barwin’s contract is up after this season, but he’s content to wait until then to sit down with general manager Rick Smith and work on a new one.

“I have no problem with going into this year without an extension,” he said. “I don’t think there will be any negotiating during the season. I’ll obviously be focused on the season and they’ll be focused on what they do, getting players and players get hurt, stuff like that. It’s something that will work itself out with Rick and my agent, and if after the year it doesn’t, then we’ll work it out then. I’m not concerned. I’m completely focused on football and I honestly believe that will work itself out.”

As for the haircut, a departure from a shaggier look he sported last season, Barwin’s version features two stripes carved over his right ear. He doesn’t expect Kubiak to follow suit.

“This is not a Kubiak thing,” Barwin said of the stripes. “Maybe I can talk him into putting a little bit of style into his flat top, but we’ll see. I doubt it.”

Kubiak didn’t see Barwin and his new ’do until the team met for the first time on Friday night.

“I guess it’s something to talk about for a couple days,” Kubiak said with a wry smile.

Notes: The Texans placed LB Darryl Sharpton on the active/physically unable to perform list (right knee). They also signed G Kasey Studdard, who missed last season with a left ankle injury.

. ... RB Arian Foster downplayed the significance of his decision to become a vegan. “I don’t know why it got so much attention,” Foster said. “There’s other vegans in the NFL.” For now, Kubiak isn’t worried about the dietary change affecting Foster’s health or performance. “I texted him about three weeks ago and said, ‘Hey Vegan, you in shape?’” Kubiak said. “He texted me back and said, ‘What the heck does that mean?’ That’s been our conversation, but he looks great.”